There is a mechanism, in which a door body is combined on a box-form base body rotatably movable between a closed position and an open position, by providing on the box-form base body a first stationary gear part for engaging with an arc-form gear part provided on an arm part of the door body, and providing on the box-form base body a second stationary gear part for engaging with a rotary gear provided on the arm part of the door body. (See Patent Document 1)
Also, there is a mechanism, in which a lid body is combined on a main body rotatably movable between a first position in which an opening of the main body is closed and a second position when the opening is open, by providing on the main body a rack surface for engaging with a pinion body provided on the side of the lid body as a movable body, and providing on the main body a gear part for engaging with a gear provided on this movable body on a part at the center of rotation of this pinion body. (See Patent Document 2)
In the mechanisms thus configured, the door body or lid body serving as the movable body can be rotated without depending on a fixed single shaft. On the other hand, there may be a case when an external force in the direction of pushing the door or lid into the box-form base body or main body is applied to the door or lid when this is in the open position or first position. In the mechanism of Patent Document 1, this force is applied directly to the rotary gear of the door body, because this rotary gear is positioned directly above the second stationary gear part. Also, in the mechanism of Patent Document 2, this force is likewise applied directly to the lid body, because the gear of this lid body is positioned directly above the gear part of the main body.